Method for finishing parts

ABSTRACT

A method and apparatus for finishing parts is disclosed. The apparatus includes a pair of concentric circular members of different radii having a horizontal axis resiliently mounted to a base for orbital vibration. Parts and a finishing media are introduced into a closed annular chamber defined by the area between the circular members. Orbital vibration causes the parts and media to move in a helical path having a substantially vertical plane around the inner member to a discharge opening. At the discharge opening the parts are separated from the media, which is then classified and portions thereof are returned to the chamber. A motor driven eccentric shaft mounted co-axially of the circular members produces the orbital motion.

This is a division, of application Ser. No. 418,556 filed Nov. 23, 1973,and now U.S. Pat. No. 3,918,212 issued Nov. 11, 1975.

BACKGROUND OF THE INVENTION

The present invention relates to vibratory devices of the type whereinblanks or parts and finishing media are introduced into a containerwhich is vibrated for the purpose of surface treating the parts. Typicaloperations which are performed in this manner are: polishing orburnishing of metal; or cleaning, abrading and deburring of the surfaceof parts using abrasive finishing media placed in intimate contact withthe parts.

In the case of conventional vibratory finishing devices, circular orelongate U-shaped bowls have generally been employed. When the bowl isvibrating, the parts and media travel in an orbital path along agenerally horizontal plane. In a preferred arrangement, means areprovided for receiving the parts and media during an upper portion oftheir travel to enable separation of the parts from the media and returnof the media by gravity to the bowl for re-use. Finishing apparatus ofthe type described is illustrated in U.S. Pat. No. 3,693,298 to Ferrara;U.S. Pat. No. 3,100,088 to Podmore et al.; and U.S. Pat. No. 3,676,958to Garland.

In such vibratory devices, very little relative motion between the mediaand parts occurs during certain portions of their travel together. Theless the amount of relative movement between the media and parts, thelonger it takes to complete the desired finishing operation. Anotherdrawback of conventional vibratory equipment is their requirement tomake use of media having a density within the range of 35 to 300 poundsper cubic foot. Since the metal surface removal rate is somewhatproportional to the weight and size of the media, such limitation on themedia is undesirable.

Another type of prior vibratory device utilizes a bowl shaped containerin which the parts and media are caused to move in a generally verticalplane. The movement is guided either by guide baffles or rotating armswithin the bowl. Examples of such devices include U.S. Patent No. RE27,084 to Balz and U.S. Pat. No. 3,611,638 to Deede. Such devices applythe vibrational energy to the parts from only one direction or requirethe use of a complicated rotating arm.

It is, accordingly, an object of the present invention to provide avibrational method in which vibrational is applied energy to the mediaand parts throughout their entire travel through the device to maximizerelative motion between the parts and media.

It is another object of the present invention to provide a vibratorymethod which has an increased material removal rate.

It is a further object of the present invention to provide a methodwhich maintains the media and parts in pressure contact for increasedmaterial removal.

It is a still further object of the present invention to provide amethod in which the parts can be accurately positioned in the media dueto the continuous rotation of the media in helical, non-crossing paths.

It is a further object to provide a vibratory device which is notlimited to the traditional range of media density.

It is a still further object to provide a method which is also capableof continuously scrubbing sand used in mold-making to remove the coatingresulting from the molding process.

Other objects of the invention will become apparent from the concludingportion of the specification.

SUMMARY OF THE INVENTION

A vibratory device for the surface finishing of parts includes a basehaving a pair of concentric circular members of different radii having ahorizontal axis resiliently mounted thereon. The circular members havetheir ends connected to form a closed annular chamber therebetween. Theparts and media are introduced into the chamber through an opening inthe outer member of the pair. A motor drives an eccentric shaft mountedco-axially of the members for causing orbital motion thereof. Theinduced orbital motion causes the parts and media in the chamber to movein a helical path around the inner member in a substantially verticalplane, toward a discharge means located at one end of the cylinders.

On reaching discharge means the parts and media are separated and themedia is classified according to a physical characteristic thereof.Selected portions of the media are returned to the chamber for re-use.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a longitudinal section of the vibrational device according tothe present invention showing the chamber formed between the inner andouter concentric members.

FIG. 2 is an end view of the vibrational device having portions cutaway.

FIG. 3 is a side view of the vibrational device according to the presentinvention showing the discharge means.

FIG. 4 is a cross-sectional view of the circular members taken along thelines 4--4 of FIG. 1.

FIG. 5 is a longitudinal section similar to FIG. 1 of a pair of circularmembers which comprise an elongated toroid.

FIG. 6 is a longitudinal section of a pair of circular members whichcomprise an elongated toroid having a longitudinal curve.

FIG. 7 is a longitudinal section of a pair of circular members whichdefine a serpentine-like chamber therebetween.

FIG. 8 is a transverse section of a pair of circular members comprisingan oval outer member and a cylindrical inner member.

FIG. 9 is a transverse section of a pair of circular members comprisinga cylindrical outer member and an oval inner member.

DETAILED DESCRIPTION

Referring now to FIGS. 1 and 2, a vibrating device 10 according to thepresent invention is shown. The device 10 includes a base 12 havingvertical support members 14 attached thereto. Mounted on the verticalsupport members is a structure comprising a pair of concentric circularmembers 16 and 18 of different radii. Members 16 and 18 have ahorizontal axis and have their ends connected to define a closed annularchamber 20 therebetween.

While the circular members 16 and 18 are illustrated as concentriccylinders in FIGS. 1-4, it will be apparent that other concentriccircular members of different radii and having a horizontal axis can beemployed, as illustrated in FIGS. 5-9. For example, an elongateddoughnut-shaped (toroidal) member, (FIGS. 5 and 6), a serpentine member(FIG. 7) or oval members (FIGS. 8 and 9)

The alternate circular members illustrated in FIGS. 5-9 operate in themanner to be described in connection with FIGS. 1-4. However, the shapevariation is effective to provide variable movement of the parts andmedia within the annular chamber 20. For example, as the mixture movesin a helical path between the serpentine shaped circular members of FIG.7, the vibrational energy transmitted to the mixture varies with thethickness of the chamber 20. Similarly, the vibrational energy varies inthe oval shaped members of FIGS. 8 and 9.

This refinement permits, in combination with multiple sized media, acoarse, medium and fine finishing action on the parts, should such bedesired.

The circular members are mounted to the vertical support members 14 byfour resilient shear mounts 24 and mounting members 26. The members arethus able to vibrate on the mountings.

A motor 28 mounted on base 12 is utilized for producing vibratory motionin the circular members. Its drive shaft 30 is connected by a belt 32 toan eccentric shaft 34 mounted co-axially of the members 16 and 18. Theshaft 34 may have a round or square cross-section as desired. However, asquare cross-section in its central portion facilitates the mounting ofa counterweight 36 thereto. The shaft is supported for rotation inbearings 38, which are rigidly connected to the inner member 16 bystruts 40. A pair of adjustable counterweights 42 mounted to the shaft34 permit adjustment of the amplitude of the vibratory motion impartedto the circular members.

The annular chamber 20, comprising the enclosed area between the members16 and 18, may have a polyurethane or other suitable replaceable lining44 to enhance the action of the media on the parts to be finished. Media48 and parts 50 are introduced into the annular chamber 20 through anopening 46 in the outer member 18. When the motor 28 causes rotation ofthe shaft 34, the circular members are caused to vibrate, producing anorbital motion within the chamber 20. As indicated schematically by thedashed arrows in FIG. 1, and as clearly illustrated in FIG. 4, thisorbital motion causes the mixture of media and parts to follow a helicalpath around the inner member 16 in a substantially vertical plane.

Located at one end of the circular member is a discharging means 52.This discharging means includes an opening 53 communicating with thechamber 20. As the mixture of parts and media reach the opening 53 theypass outwardly from the chamber and are processed in a manner to besubsequently described. As will be recognized by those skilled in theart, the length of time required for a part to travel through thechamber 20 will be determined by the amplitude of vibratory motionimparted to the circular members and by the location at which the partis introduced into the chamber. Introducing the parts further fromdischarge means 52 increases the time they remain in the chamber 20.

Although helical motion of the parts and media is preferred so that acontinuous operation is possible, it is also contemplated to operate thedevice as a batch processer. For batch processing, parts can beintroduced into the chamber 20 and by adjusting the eccentricity of theshaft the media and parts can be made to travel a completely circularpath around and around in the chamber 20 with no horizontaldisplacement. After the parts have achieved a desired finish they can beremoved from the chamber through the opening 46 or the discharge means.

Located at the end of the circular members, near a bottom portionthereof opposite the discharge means 52, is a media drain 54 forremoving the contents of the chamber for cleaning, relining or othermaintenance operations.

Referring now to FIGS. 2 and 3, the details of the discharge means 52will be described. As the mixture of media 48 and parts 50 dischargesfrom the chamber 20 through opening 53, it is deposited onto aseparating screen 60. Simultaneously the mixture is subjected to aliquid shower 58 for facilitating the separation of the parts from themedia. The part being substantially larger than the media, separation iseffected by selecting an appropriate mesh size for screen 60 to permitthe media to pass downwardly through the screen to a chamber 61.

The separating screen 60 and the chamber 61 are isolated from thevibrational motion of the circular members by shear mounts 62 and 64. Anindependent vibrational system is provided for effecting separation ofthe parts and media including a motor and an eccentric fly wheel 66mounted to the underside of chamber 61. As the media and parts pass onto the classifying screen 60, they are subject to vibration from theeccentric fly wheel 66. The parts travel along the screen 60 due to thevibration, until they reach a discharge chute 68, where they aretransferred to conveying means for further processing. The media passesdownwardly into the chamber 61 onto a second classifying screen 72disposed therein. Media which is too large to pass through theclassifying screen 72 is vibrated along the path indicated by the arrows73 to a duct 74 communicating with the annular chamber 20. Thus media ofa predetermined minimum size is returned to the chamber 20 for re-use.Media, which through repeated usage has become small enough to passthrough the classifying screen 72, is collected in a V-shaped trough 76along with the liquid from the shower 58. This waste fluid mixture isremoved from the device through a drain pipe 78 to appropriate disposalmeans.

Referring to FIG. 2, a third vibratory device 80, of standard design, ismounted to the underside of discharge opening 53 to increase the flowrate of parts and media as they are discharged from the chamber 20 ontothe classifying screen 60.

Briefly reviewing operation of the device, it will be apparent thatmedia and parts which are to receive surface treatment are introducedinto the annular chamber 20 through opening 46. The motor 28 causesrotation of the eccentric shaft 34 producing orbital motion of thecylindrical assembly. Such motion causes energy to be transmitted to thematerial within the annular chamber 20 from both the inner circularmember 16 and the outer member 18. This vibrational energy causes themedia and parts to move relative to each other for surface treatment ofthe parts and further causes the mixture to travel a helical path aroundand around the inner member until it reaches the discharge end of theassembly.

When the mixture is discharged, it travels over a separating screen 60which permits the media, but not the parts, to pass downwardly into achamber 61. The finished parts are delivered to a discharge chute 68.The media is further classified by a second screen 72, portions of whichare returned to the annular chamber 20 for re-use, while the balance isdischarged through drain pipe 78.

While the above description represents the primary use of the presentinvention, it can also be employed for scrubbing sand to remove thecoating which results from the molding processes employed in making theparts. For such purposes, the sand is fed into the chamber 20 andallowed to travel therethrough to the discharge means. The vibratoryaction of the device is effective to scrub the sand and remove themolding binder permitting the sand to be re-used in the molding process.

While I have shown and described an embodiment of this invention in somedetail, it will be understood that this description and illustration areoffered merely by way of example, and that the invention is to belimited in scope only by the appended claims.

I claim:
 1. A method of surface finishing parts comprising the steps of:introducing parts and finishing media into an upper portion of a closedannular chamber defined by a pair of horizontally oriented concentriccircular members of different radii; vibrating said chamber to produceorbital motion therein for causing said parts and media to movecircumferentially within said chamber; discharging said parts and mediafrom said chamber at said upper portion; and separating said parts fromsaid media including the sub-steps of classifying the media according toa physical characteristic thereof, and returning selected portions ofthe media to said chamber at a bottom portion thereof by vibrational andgravitational force.
 2. The method of claim 1 wherein said parts andmedia move in a helical path in said chamber in a substantially verticalplane.
 3. The method of claim 1 wherein said parts and media move in acircular path in said chamber in a substantially vertical plane.